In heterogeneous network (HetNet) scenarios using standards like e.g. Third Generation Partnership Project Long Term Evolution (3GPP LTE) standard, so-called Pico base stations with their Pico cells are placed under the coverage of a so-called Macro base station. A Pico base station typically covers a small area e.g. in buildings, train stations or aircrafts or outside due to its lower power, whereas a Macro base station covers a larger area than a Pico base station, as e.g. an outdoor area.
In the downlink the interference on user terminals served by a Pico base station is usually dominated by the Macro base station that covers the Pico cell.